[Rsvp] Re: help

[Steven Berson]

OK, I normally don't respond to my own messages, but I misunderstood 
the question.  I understood the question to be asking how to use RSVP 
to reserve resources for IPSEC data flows.  I don't recall seeing the 
original message, but as I read David's response carefully, it appears 
that the question really is about using IPSEC to protect the RSVP 
protocol messages themselves.  David gives a good answer to the latter
question.

Regards,
Steve

On Tue, 4 Mar 2003, Steven Berson wrote:

> Actually, RSVP can be used with IPSEC.  See RFC 2207, ``RSVP 
> Extensions for IPSEC Data Flows''.
> 
> Regards,
> Steve
> 
> On Tue, 4 Mar 2003, David Charlap wrote:
> 
> > Harish Kumtakar wrote:
> > > 
> > >      Why IPSEC can not be used in RSVP to care of security. Please throw 
> > > some light on this aspect.
> > 
> > The reason it isn't in classical RSVP is because IPSEC secures two 
> > endpoints.  But the nature of RSVP is such that packets are supposed to 
> > be intercepted and processed by transit routers.
> > 
> > An RSVP router does not send a Path message to his neighbor.  He sends 
> > it to the ultimate destination address, with the router-alert option, so 
> > that RSVP-aware routers along the way may intercept and process the 
> > packet.  This is fundamentally incompatible with IPSEC - where the 
> > packet is encrypted such that transit routers can not intercept anything.
> > 
> > If you want to use IPSEC with RSVP, then you must send packets directly 
> > to neighbors and abandon the use of router-alert.  This isn't a problem 
> > for RSVP-TE, since the presence of non-RSVP routers isn't permitted in 
> > an MPLS/RSVP-TE network.  But it eliminates the ability for classical 
> > RSVP to work over networks with non-RSVP nodes - something that is a key 
> > goal of the RSVP protocol.
> > 
> > IPSEC also makes multicast much more CPU intensive.  If every packet is 
> > encrypted, then you can't simply generate one Path message for 
> > transmission to all downstream nodes in a multicast group.  You have to 
> > generate multiple separate packets and encrypt them individually.
> > 
> > -- David
> > 
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> 
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